This invention relates to compositions containing multivalent silver compounds that have been exposed to ozone, and more particularly to aqueous solutions containing ozone-activated tetrasilver tetroxide.
It is conventionally understood that water, particularly standing bodies of water, can be an effective breeding ground or reservoir for a variety of undesirable microbes. Thus, a wide variety of water treatment systems have been developed to disinfect potable water and/or maintain it at a safe level.
Perhaps the most common disinfection method for drinking or recreational water is chlorination. However, it has been found that chlorine has an objectionable odor, and can cause skin irritations and serious eye irritations to users of recreational bodies of water, such as pools, spas, etc. More importantly, chlorine forms trihalomethanes in the presence of organic materials and these compounds present a potential health threat due to their carcinogenicity and mutagenicity. Because of the long term health threat and objectionable physical properties of chlorine, a number of alternate water treatment systems that operate without chlorine have been developed in recent years.
Another gas used to disinfect water is ozone. According to U.S. Pat. No. 4,176,061 to Stopka, the ability of ozone to purify drinking water has been appreciated for some time. Stopka cites a number of references that teach the advantages of using ozone rather than chlorine to decontaminate water. What Stopka does not disclose is that ozone, like chlorine, has some disadvantages. Perhaps most significant of these disadvantages is that ozone, as a gas, can dissipate from water over time, leaving the water once again susceptible to contamination by various pathogens.
A number of water disinfection systems rely on the oligodynamic effect provided by the addition to water of, e.g., transition metals such as silver.
For example, U.S. Pat. No. 4,608,247 to Heinig, Jr. discloses water treatment systems comprising exposing the water to a material which erodes to provide particulate silver in the water. Although the particulate silver is said to be ionic, and the patent does not disclose the valency of the ions formed by erosion, other references, such as Antelman, xe2x80x9cSilver (II, III) Disinfectants,xe2x80x9d Soap/Cosmetics/Chemical Specialties, pp. 52-59 (March 1994) at page 52, third paragraph, suggest that trace ions formed from silver metal are monovalent.
U.S. Pat. No. 5,352,369 to Heinig, Jr. acknowledges that water treatment systems like that disclosed in Heinig""s earlier ""247 patent are only partially effective in avoiding the use of chlorine as an antimicrobial agent, in that such systems often require the addition of reduced amounts of chlorine to water treated by such systems. The ""369 patent purports to avoid this limitation on prior silver-based systems, in providing a method of treating water by generating an active oxidizer in the water which is capable of attacking and killing a wide range of microorganisms therein. The method comprises exposing the water to a silver catalyst in the presence of oxygen to form an active oxidizer in the water and, in some instances to also release silver ions (presumably monovalent silver ions as discussed above) therein via an erosion process similar to that set forth in Heinig""s ""247 patent. The silver catalyst utilized in the method comprises an alumina matrix having between approximately 0.1% and 5% by weight of elemental silver chemically deposited thereon. The oxygen utilized in the method preferably also comprises ozone.
U.S. Pat. Nos. 5,017,295, 5,073,382, 5,078,902, 5,089,275, 5,098,582, 5,211,855 and 5,223,149 to Antelman disclose water treatment methods comprising adding multivalent silver compounds to water.
U.S. Pat. No. 5,211,855 to Antelman discloses and claims a water treatment method comprising adding tetrasilver tetroxide to water bodies, such as reservoirs. At column 1, Antelman discloses that his previous patents were incorrect in identifying the antimicrobial agent as silver (II) oxide (i.e., AgO), when it is actually tetrasilver tetroxide (i.e., Ag4O4), wherein each molecule comprises one pair of monovalent silver atoms and one pair of trivalent silver atoms.
U.S. Pat. No. 5,223,149 to Antelman discloses the use of trivalent silver compounds as bactericidal and algicidal agents in water treatment. Antelman asserts that these trivalent silver compounds are an improvement over his earlier divalent silver compounds, which are disclosed and claimed in his earlier U.S. patents identified above. Antelman at the paragraph bridging columns 1-2 teaches that oxidizing agents are not required to be used with the trivalent silver compounds.
Despite the foregoing developments, there is still room in the art for improved water treatment systems.
All references cited herein are incorporated herein by reference in their entireties.
The invention provides an ozonated form of the compound tetrasilver tetroxide, a water disinfection method employing the ozonated tetrasilver tetroxide and compositions comprising the ozonated tetrasilver tetroxide. Examples of compositions of the invention include beverages and disinfectants.
In addition, the invention provides a method for increasing the half-life of ozone in water, said method comprising providing tetrasilver tetroxide in the water along with the ozone.